The present invention relates to a transparent butadiene-based rubber-reinforced resin and a composition containing the same, and more particularly, to a butadiene-based rubber-reinforced resin which exhibits an excellent transparency and contains a rubber phase having specific average particle size and particle size distribution, and a butadiene-based rubber-reinforced resin composition for laser marking having an excellent white tinting property.
In recent years, transparent materials have been increasingly demanded in application fields such as light electric devices or electronic devices, especially audio-related devices or office automation (OA) devices. The transparent materials used in such applications have been required to have not only transparency but also mechanical strength such as impact resistance. Styrene-based resins obtained by polymerizing or copolymerizing an aromatic vinyl compound are brittle, i.e., are deteriorated in mechanical strength nevertheless excellent transparency thereof. In order to enhance the mechanical strength, it has been attempted to blend rubber polymers with the styrene-based resins to prepare rubber-reinforced resins. However, molded products obtained from such resins are opaque and fail to exhibit a sufficient impact resistance.
The deteriorated transparency of the rubber-reinforced resins obtained by blending rubber polymers with the styrene resins is caused by the difference in refractive index therebetween. Therefore, in order to obtain rubber-reinforced resins having a high transparency, it is required that the refractive index of the rubber component as domain is identical to that of the resin component as matrix. For example, when a butadiene-based rubber having an excellent reinforcing property but a low refractive index is used as the rubber component, it is required to use polymethyl methacrylate (PMMA) having a low refractive index as the resin component. However, since the PPMA itself has a poor mechanical strength, the obtained rubber-reinforced PMMA is still insufficient in rubber-reinforcing effect, and fails to show a satisfactory mechanical strength.
As rubber-reinforced resins which are improved in mechanical strength, there have be marketed so-called transparent ABS resins using as the resin component, methyl mechacrylate/styrene/acrylonitrile (MMA/ST/AN) tercopolymer having a refractive index close to that of the butadiene-based rubber. However, the conventional transparent ABS resins are insufficient in transparency, and show ill-balanced mechanical properties. Further, as conventionally known, these transparent ABS resins fail to exhibit a white tinting property by laser marking.
As a result of the present inventors"" earnest studies to solve the above problem, it has been found that when the rubber phase as domain has specific average particle size and particle size distribution, the obtained butadiene-based rubber-reinforced resin and its composition can show an enhanced transparency and are free from the above disadvantages.
The present invention has been attained based on the above finding.
An object of the present invention is to provide a transparent butadiene-based rubber-reinforced resin and its composition which are free from the problems of the conventional styrene-based resins, and can exhibit excellent mechanical properties and high laser marking property in addition to inherent transparency and moldability of the styrene-based resins.
To accomplish the aim, in a first aspect of the present invention, there is provided a transparent butadiene-based rubber-reinforced resin produced by graft-polymerizing monomer components (b) comprising as main components an aromatic vinyl compound, a vinyl cyanide compound and an acrylic or methacrylic acid ester in the presence of particles of a butadiene-based rubber (a), said butadiene-based rubber-reinforced resin comprising, when observed by an electron microscope, a rubber phase having an average particle size of 150 to 350 nm and containing particles having a particle size of less than 150 nm in an amount of not more than 30% by weight and particles having a particle size of more than 350 nm in an amount of not more than 30% by weight; and containing acetone solubles having an intrinsic viscosity [xcex7] of 0.2 to 0.4 dl/g when measured at 30xc2x0 C. in methyl ethyl ketone.
In a second aspect of the present invention, there is provided a transparent butadiene-based rubber-reinforced resin produced by graft-polymerizing monomer components (b) comprising as main components an aromatic vinyl compound, a vinyl cyanide compound and an acrylic or methacrylic acid ester in the presence of particles of a butadiene-based rubber (a) having an average particle size of 150 to 350 nm and containing particles having a particle size of less than 150 nm in an amount of not more than 30% by weight and particles having a particle size of more than 350 nm in an amount of not more than 30% by weight, said butadiene-based rubber-reinforced resin containing acetone solubles having an intrinsic viscosity [xcex7] of 0.2 to 0.4 dl/g when measured at 30xc2x0 C. in methyl ethyl ketone.
In a third aspect of the present invention, there is provided a transparent butadiene-based rubber-reinforced resin composition, comprising:
the transparent butadiene-based rubber-reinforced resin (A) as defined in the first or second aspect; and
a thermoplastic resin made of a copolymer (B) which is produced by copolymerizing an aromatic vinyl compound, a vinyl cyanide compound and an acrylic or a methacrylic acid ester, and has an intrinsic viscosity [xcex7] of 0.2 to 0.4 dl/g when measured at 30xc2x0 C. in methyl ethyl ketone,
said transparent butadiene-based rubber-reinforced resin being contained in an amount of 3 to 30% by weight based on the total weight of the composition.
In a fourth aspect of the present invention, there is provided a butadiene-based rubber-reinforced resin composition for laser marking, comprising:
30 to 100 parts by weight of the transparent butadiene-based rubber-reinforced resin (A) according to the first and second aspect; and
70 to 0 parts by weight of a thermoplastic resin other than said the transparent butadiene-based rubber-reinforced resin (A), with the proviso that the total amount of (A) and (C) is 100% by weight.